34 WORKING WITH SAMPLE DATA Interpretation: There is a 2% chance that a sample of 72 homes will produce a sample proportion of 12% or less who do most of their grocery shopping on Saturday. While it is possible that the proportion of shoppers will have 12% or less who do most of their grocery shopping on Saturdays, it is not very likely to occur. Point and Interval Estimates Sometimes what we need is a good estimate of the value for an important variable. How much income do we anticipate generating during the next fiscal year? What proportion of a region's population served by the com- munity's hospital will require emergency room treatment during the next month? A point estimate is the single value that best approximates the value of a population parameter of interest. If we take a random sample _ from a population and compute the sample mean, x , this would serve as a point estimate of the true population mean, . If we want to esti- mate the proportion of a population that falls in a particular category, _